The terminology “conductive yarn” (or digital yarn) refers to yarns which can conduct electrons to transfer information as well as be woven or knitted so that clothes can be made of the conductive yarns. Weaves (cloth or stock made by the interlacing of warps and threads) or knits (cloth or stock made by the interlacing of yarns or threads in a series of connected loops) made of conductive yarns can act as a circuit of a circuit board of an electronic appliance to connect electronic modules to each other, thereby enabling data transmission. That is, the conductive yarns can connect a bio-signal sensor with a communication medium or a memory, or with an electronic module to enable computing. Thus, the conductive yarns can be used in wearable computer fields, and it is expected that they will be used more in the future.
Recently, there are attempts to provide a computer as a part of clothes for the purpose of info-communication. One of such attempts in the early stage was to attach metal parts of a computer to the clothes. Lately, a computer is attached to clothes so that its constitutional parts are not exposed. Furthermore, there is an approach to assemble computer parts with materials of clothes so that a computer can be provided as a part of the clothes.
In order to fabricate a piece of clothes in which a wearable computer is provided as a part of the clothes, conductive textiles (or digital textiles) capable of being used in info-communication have to be produced and, first of all, conductive yarns capable of being used in info-communication have to be produced in order to make the conductive textiles. To produce the conductive yarns, metal filaments are typically used. The term metal filament refers to a fine metal wire.
However, conventional processes of producing conductive yarns using metal filaments have several drawbacks. That is, high rigidity and brittleness of metal often breaks the metal filaments during the process, thereby worsening productivity and thus raising production costs. In addition, the conductive yarns tend to be broken during weaving and/or knitting, thereby degrading weaving and/or knitting efficiency. Even though the conductive yarns are made into a piece of clothes, some of the conductive yarns used, for example, in an elbow part of the clothes easily break owing to repeated bending so that the clothes lose info-communication ability. Furthermore, in view of the characteristics of metal, it is difficult to wash the clothes. Accordingly, there are real demands for advanced processes of producing conductive yarns which can overcome such problems.